An image forming device that uses only one temperature sensor to detect temperatures of the recording sheet and a rotation member for fixing, and can perform the temperature adjustment control carefully in detail during the image forming operation. The CPU 61 performs the temperature adjustment control 1 by executing the temperature adjustment program 64b (step S109), then executes the paper passing judgment program 64a to judge whether or not paper is passing (step S110). As far as it judges that no paper is passing (NO in step S110), the CPU 61 continues to perform the temperature adjustment control 1 by executing the temperature adjustment program 64b. When it judges that paper is passing (YES in step S110), the CPU 61 performs the temperature adjustment control (step S112).